Implantable pulse generator and method having adjustable signal blanking

Abstract

An implantable pulse generator senses a cardiac signal, identifies cardiac events in the cardiac signal, and starts a blanking interval including a repeatable noise window blanking interval in response to each cardiac event. When noise is detected during the repeatable noise window blanking interval, the noise window blanking interval is repeated. In one embodiment, the duration of repeated repeatable noise window blanking intervals is summed and compared to a pacing escape interval. When the sum is greater than the pacing escape interval, asynchronous pacing pulses are delivered until the noise ceases. Alternatively, when the sum is greater than the pacing escape interval, the pace escape interval is repeated.

1. An implantable pulse generator, comprising:
 a signal sensor to sense a first cardiac signal; 
 a blanking window initiator coupled to the signal sensor, the blanking window initiator adapted to identify cardiac events in the first cardiac signal and to start a blanking interval when a cardiac event is identified in the first cardiac signal, the blanking interval including a repeatable noise window blanking interval; 
 a noise detector coupled to the signal sensor and the blanking window initiator, the noise detector adapted to analyze the first cardiac signal to detect noise identified by a predetermined noise frequency range in the first cardiac signal during the repeatable noise window blanking interval, wherein the blanking window initiator is adapted to repeat the repeatable noise window blanking interval when the noise detector detects noise in the first cardiac signal during the repeatable noise window blanking interval; and 
 a pace output circuit, coupled to the one or more electrodes, to deliver pacing pulses including pacing pulses separated by a pacing escape interval, 
 wherein the noise detector is adapted to sum repeated repeatable noise window blanking intervals to give a duration of the repeatable noise window blanking intervals and to issue a first signal to start delivery of asynchronous pacing pulses when the duration of the repeated repeatable noise window blanking intervals is greater than the pacing escape interval. 
 
   
   
     2. The implantable pulse generator of  claim 1 , wherein the noise detector is adapted to issue a second signal to stop delivery of asynchronous pacing pulses when the noise is not detected. 
   
   
     3. The implantable pulse generator of  claim 1 , wherein the noise detector is adapted to analyze the first cardiac signal to detect noise identified by a predetermined noise frequency range programmable for frequencies greater than 50 Hz. 
   
   
     4. The implantable pulse generator of  claim 1 , wherein the blanking window initiator is adapted to identify sensed cardiac events and paced cardiac events, and the blanking window initiator is adapted to adjust the blanking interval to a first overall duration when a paces cardiac event is identified and to a second different overall duration when a sensed cardiac event is identified. 
   
   
     5. The implantable pulse generator of  claim 4 , wherein the blanking window initiator is adapted to end the repeatable noise window blanking interval concurrently with the first overall duration of the blanking interval. 
   
   
     6. The implantable pulse generator of  claim 5 , wherein the second overall duration includes a first timed interval, and wherein the blanking window initiator is adapted to start the repeatable noise window blanking interval after the first timed interval of the second overall duration. 
   
   
     7. The implantable pulse generator of  claim 6 , further comprising a first cardiac lead, coupled to the signal sensor, for sensing the first cardiac signal, and a second cardiac lead, coupled to the signal sensor, for sensing a second cardiac signal, wherein the blanking window initiator is adapted to start the blanking interval to blank at least the second cardiac signal. 
   
   
     8. An implantable pulse generator, comprising:
 a signal sensor to sense a first cardiac signal; 
 a blanking window initiator coupled to the signal sensor, the blanking window initiator adapted to identify cardiac events in the first cardiac signal and to start a blanking interval when a cardiac event is identified in the first cardiac signal, the blanking interval including a repeatable noise window blanking interval; 
 a noise detector coupled to the signal sensor and the blanking window initiator, the noise detector adapted to analyze the first cardiac signal to detect noise identified by a predetermined noise frequency range in the first cardiac signal during the repeatable noise window blanking interval, wherein the blanking window initiator is adapted to repeat the repeatable noise window blanking interval when the noise detector detects noise in the first cardiac signal during the repeatable noise window blanking interval; and 
 a pace output circuit, coupled to the one or more electrodes, to deliver pacing pulses including pacing pulses separated by a pacing escape interval, 
 wherein the noise detector is adapted to sum repeated repeatable noise window blanking intervals to give a duration of the repeatable noise window blanking intervals and to compare the duration of the repeatable noise window blanking intervals to the pacing escape interval, and wherein the noise detector is adapted to repeat the pacing escape interval when the duration of the repeatable noise window blanking intervals is greater than the pacing escape interval. 
 
   
   
     9. The implantable pulse generator of  claim 8 , wherein the noise detector is adapted to issue a first signal to resume pacing pulse delivery after one pacing escape interval after the noise signal ceases. 
   
   
     10. The implantable pulse generator of  claim 8 , wherein the noise detector is adapted to analyze the first cardiac signal to detect noise identified by a predetermined noise frequency range programmable for frequencies greater than 50 Hz. 
   
   
     11. The implantable pulse generator of  claim 8 , wherein the blanking window initiator is adapted to identify sensed cardiac events and paced cardiac events, and the blanking window initiator is adapted to adjust the blanking interval to a first overall duration when a paces cardiac event is identified and to a second different overall duration when a sensed cardiac event is identified. 
   
   
     12. The implantable pulse generator of  claim 11 , wherein the blanking window initiator is adapted to end the repeatable noise window blanking interval concurrently with the first overall duration of the blanking interval. 
   
   
     13. The implantable pulse generator of  claim 12 , wherein the second overall duration includes a first timed interval, and wherein the blanking window initiator is adapted to start the repeatable noise window blanking interval after the first timed interval of the second overall duration. 
   
   
     14. The implantable pulse generator of  claim 13 , further comprising a first cardiac lead, coupled to the signal sensor, for sensing the first cardiac signal, and a second cardiac lead, coupled to the signal sensor, for sensing a second cardiac signal, wherein the blanking window initiator is adapted to start the blanking interval to blank at least the second cardiac signal. 
   
   
     15. A method, comprising:
 sensing a first cardiac signal; 
 identifying cardiac events in the first cardiac signal; 
 starting a blanking interval when one of the cardiac events is identified, the blanking interval including a repeatable noise window blanking interval; 
 detecting noise in the first cardiac signal during the repeatable noise window blanking interval, the noise identified by a predetermined noise frequency range; 
 repeating the repeatable noise window blanking interval when the noise is detected; 
 summing a duration of repeated repeatable noise window blanking intervals; 
 comparing the duration to a pacing escape interval; and 
 delivering asynchronous pacing pulses when the duration is greater than the pacing escape interval. 
 
   
   
     16. The method of  claim 15 , comprising stopping the asynchronous pacing pulses when the noise is not detected. 
   
   
     17. The method of  claim 15 , wherein identifying the cardiac events comprises identifying a nature of each of the cardiac events, and further comprising adjusting a duration of the blanking interval based on the nature of the each of the cardiac events. 
   
   
     18. The method of  claim 17 , wherein identifying cardiac events in the first cardiac signal comprises identifying intrinsic cardiac events and paced cardiac events, and adjusting the duration of the blanking interval comprises adjusting the blanking interval to a first overall duration when each of the paced cardiac events is identified and adjusting the blanking interval to a second overall duration when each of the intrinsic cardiac events is identified. 
   
   
     19. The method of  claim 18 , further comprising ending the repeatable noise window blanking interval concurrently with the first overall duration of the blanking interval. 
   
   
     20. The method of  claim 19 , wherein the second overall duration includes a first timed interval, and further comprising starting the repeatable noise window blanking interval after the first timed interval of the second overall duration. 
   
   
     21. The method of  claim 20 , further comprising programming the predetermined frequency range to include frequencies greater than 50 Hz. 
   
   
     22. A method, comprising:
 sensing a first cardiac signal; 
 identifying cardiac events in the first cardiac signal; 
 starting a blanking interval when one of the cardiac events is identified, the blanking interval including a repeatable noise window blanking interval; 
 detecting noise in the first cardiac signal during the repeatable noise window blanking interval, the noise identified by a predetermined noise frequency range; 
 repeating the repeatable noise window blanking interval when the noise is detected; 
 summing a duration of repeated repeatable noise window blanking intervals; 
 comparing the duration to a pacing escape interval; and 
 repeating the pace escape interval when the duration is greater than the pacing escape interval. 
 
   
   
     23. The method of  claim 22 , further comprising resuming pacing after one pacing escape interval after the noise signal ceases. 
   
   
     24. The method of  claim 22 , wherein identifying the cardiac events comprises identifying a nature of each of the cardiac events, and further comprising adjusting a duration of the blanking interval based on the nature of the each of the cardiac events. 
   
   
     25. The method of  claim 24 , wherein identifying cardiac events in the first cardiac signal comprises identifying intrinsic cardiac events and paced cardiac events, and adjusting the duration of the blanking interval comprises adjusting the blanking interval to a first overall duration when each of the paced cardiac events is identified and adjusting the blanking interval to a second overall duration when each of the intrinsic cardiac events is identified. 
   
   
     26. The method of  claim 25 , further comprising ending the repeatable noise window blanking interval concurrently with the first overall duration of the blanking interval. 
   
   
     27. The method of  claim 26 , wherein the second overall duration includes a first timed interval, and further comprising starting the repeatable noise window blanking interval after the first timed interval of the second overall duration. 
   
   
     28. The method of  claim 27 , further comprising programming the predetermined frequency range to include frequencies greater than 50 Hz.